JPH0683222B2 - Network control method - Google Patents

Description

The present invention relates to a network control method in a token bus type network system for transferring a communication right by a token which is a communication right transfer instruction.

[Prior Art] In recent years, a local area network system for connecting a number of communication control devices (hereinafter referred to as nodes) sharing a single transmission line and performing data communication between these nodes, a so-called "LAN" has been developed. It is flourishing. Among the various communication methods in LAN, the token passing method is particularly excellent in that it can provide communication service to all nodes evenly when the network is in a high traffic state, and therefore does not cause a decrease in transmission efficiency. It is a thing.

An example of the system configuration of this LAN is shown in FIG.

In the figure, reference numeral 1 denotes transmission lines 100 to 160, and each node A constituting a LAN.
G. Hosts A to G (200 to 260) for processing transmission information are connected to the nodes A to G (100 to 160), respectively.

There are two types of token circulation control, a "token ring" system and a "token bus" system, depending on the shape of the network.
Transmission is formed in a single linear state, and transmission data sent from one node is transmitted to all other nodes connected to the network transmission line (transmission line 1 in FIG. 2) almost at the same time. Be received.

Therefore, the destination node address is always added to the beginning of the data to be transmitted including the above token command, and this is compared with the address value uniquely assigned to each node, and the node assigned to the own node When it matches the address, the transmission data is taken as the data addressed to the own node, or after the transmission data is indiscriminately taken, the above address comparison is performed, and when it matches, the data is officially addressed to the own node. deal with.

In this token bus system, a node to which a token should be passed next (downstream node) is generally "a node that is the closest to its own node address and has a small (or large) address value. A node having a maximum (or minimum) address value is defined as a node having a (or maximum value) address.

FIG. 3 shows an example of token circulation of the LAN shown in FIG. In the case of the movement within the arc, the token circulation direction is only reversed. In addition, if there are inoperable nodes due to a failure or power down in the network, it is necessary to skillfully avoid them and perform token circulation. That is, if there is an inoperable node, remove this node from the network configuration, remove it from the token cyclic ring (that is, perform degenerate operation), select another appropriate node as the node to which the token should be passed thereafter, and select it. It is necessary to switch. In the system shown in FIG. 2, for example, when the node B110 and the node F150 are inoperable nodes, an example of token circulation is shown in FIG.

As shown in the figure, it is necessary to circulate the token while avoiding the inoperable node.

Now, in order to start the token circulation, it is necessary to generate a token at any node in the network and pass it to the next node. Regarding this, in a general token bus type network system, at the time of start-up or when the token disappears, a token is generated at a specific node that constitutes the network, and the token is freely generated so that data can be transmitted subsequently. Take a method that allows you to send.

It is necessary for the specific node to detect the node to which the token should be newly transferred. Especially at power-up, it is completely unknown which node can transmit, and the operation is confirmed for all nodes existing in the network. Was going.

[Problems to be Solved by the Invention] In the above-described conventional technique, since it takes a lot of time to confirm the operation of each node, it is performed only at regular time intervals, and the nodes constituting the network can operate. Even then, data could not be transmitted unless a certain period of time passed.

[Means for Solving Problems] In order to solve the above problems, the present invention is a transmission device in which a plurality of transmission devices are connected to each other by a communication medium and a communication right is acquired by a token that is a communication right transfer instruction. In the network control method of a network system in which a token is lost, when a specific transmission device among the transmission devices that make up the network loses a token due to the entry of a new transmission device into the network and when the system is started up, a new token The specific transmission device uses the address value of its own device as an initial value, and shifts the address value one by one from the initial value to set the destination address, and the destination address setting device sets the destination address. To check whether the transmission device can operate with respect to the transmission device that uses the specified address value as a unique address value When a response signal is returned from the transmission means for transmitting the transmission frame and the transmission device for transmitting the transmission frame after the transmission frame is transmitted by the transmission means, the address value of the transmission device for transmitting the transmission frame is set in the network configuration. Storage means for storing in a table, and control means for repeatedly executing setting of an address value by the destination address setting means, transmission of a transmission frame by the transmission means and storage of an address value by the storage means for all transmission devices. , Notification means for notifying the plurality of transmission devices forming the network of the address value stored in the network configuration table.

[Operation] In such a configuration, even if the transmission command is sent to all the transmission devices, if there is no transmission device returning the response signal, the address value is set, the transmission frame is transmitted, and the transmission frame is transmitted again from the beginning. When there is a transmission device that repeatedly stores the address value for all transmission devices and sends back a response signal to the transmission command, the token transmission process is performed to enable data transmission, and there are multiple transmission devices that make up the network. When delegating the token, each of the transmission devices sends the token to another transmission device based on the contents of the network configuration table notified from the specific transmission device.

First Embodiment Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a node according to an embodiment of the present invention, which constitutes the network system shown in FIG. The description of FIG. 2 is omitted because it has been described above.

In FIG. 1, 1 is a LAN network transmission line, 2 is a node which is a transmission control device, and 3 is various computer equipment and office equipment (hereinafter referred to as a host) connected to the node 2.

The node 2 is a communication circuit that performs data communication with the transmission line 1.
12, a receiving circuit 11, a token discriminating circuit 4 for discriminating whether or not the received data in the receiving circuit 11 is a token, overall control of a node, processing of transmitted data, decoding of received data, timing control of disassembly and communication operation, etc. Control unit (hereinafter CP
5), a transmission / reception data, a memory circuit 6 for storing the control procedure of the CPU 5, an interface circuit 7 with the host 3, a switch for setting a unique address number (node address) for each node, etc. It comprises an address setting unit 8, a network configuration table 9 for storing network configuration such as address information of each configuration node of the network, and a destination address discriminating circuit 13.

The address value set in the address setting unit 8 and the node information in the network configuration table 9 are read by the CPU 5 and used as a destination address, a source address, etc. at the time of transmission / reception.

In addition, a timer circuit shown by a chain line in the master node described later.
10 is provided, and when no token is detected for a certain period of time, the fact is notified to the CPU 5.

The data to be transmitted from the host 3 can be transmitted to the transmission line 1 via the transmission circuit 12 only when the reception circuit 11 receives the token addressed to the own node and acquires the transmission right.

The data to be transmitted is temporarily stored in the memory circuit 6 in the node 2 and is converted into an appropriate format (packet) as communication data.
The destination node address is added as the destination address value, and the setting value of the address setting circuit 8 is added as the source address, and then sent to the transmission line 1.

For receiving the transmission information, the communication data on the transmission line 1 is received by the receiving circuit 11
When the destination address discriminating circuit 13 checks the destination address value in the received data and determines that it is the set value of the address setting circuit 8 in the own node, that is, the data is addressed to the own node, this is notified to the CPU 5. Then, this data is taken into its own node, and after being somewhat decomposed and edited by the CPU 5, it is delivered to the connected host 3 as necessary.

Based on the above hardware configuration and the principle of token passing described above, each node in the network transfers tokens to downstream nodes one after another, so that communication that shares one transmission line is performed. is there. When all the nodes in FIG. 2 are up, the token circulates as shown in FIG.

The network system configuration of this embodiment will be described below with the configuration shown in FIG.

The structure of the transmission frame circulating in the network system of this embodiment is shown in FIGS. 5 (A) and 5 (B).

In the figure, 200 is a token frame, 201 is a source address (hereinafter referred to as SA), 202 is a destination address (hereinafter referred to as DA), 203 is a token code representing a token frame, 2
05 is a transmission code representing a data frame, and 206 is transmission information.

The data transmission control of this embodiment will be described below with reference to the flow chart of FIG.

When the node device is powered on, whether or not it is the only specific node (hereinafter referred to as the master node) in the network that can first generate a token in step S1 and send (transfer) it to another node. If it is the master node, the process proceeds to step S2 to execute the network construction process,
In the subsequent step S3, the timer circuit 10 is started.

When the network construction process is completed, the step
Proceed to S4, set the own node address in SA201, set the token code in 203, determine the downstream node address to which the token should be transferred by referring to the network configuration table 9 constructed in step S3, and set it in DA202. Generate the token frame 200. Then, this is sent to the transmission line 1 via the transmission circuit 12, the transmission right is transferred to the downstream node, and then the process proceeds to step S5.

On the other hand, if the master node is not the master node in step S1, the process proceeds to step S5.

In step S5, it is monitored whether or not the transmission frame is received from the transmission line 1. If the transmission frame is not received, the step is performed.
In S6, it is checked whether or not it is the master node, and if it is the master node, in step S7 it is checked whether or not there is a notification by the time-out interrupt from the timer circuit 10. Timer circuit 10
Is set to a time sufficient for the token to complete one cycle of the network, or the maximum holding time of the token per node. Even if the predetermined time set in the timer circuit 10 has elapsed, the token detection circuit 4 detects the token. If not, the network configuration is changed and the process returns to step S2 to execute the network construction process. If it is not the time-out or if it is not the master node, the process proceeds to step S5, and the transmission frame is received.

When the transmission frame is received in step S5, the process proceeds to step S8, and the transmission code area (203, 205) in the transmission frame received by the token determination circuit 4 is checked to see whether or not it is the token code 203. When the token frame is received, the process proceeds to step S5, and if it is the master node, the timer of the timer circuit 10 is restarted. And step S10
Then, the destination address determination circuit 13 determines that the DA202 in the received frame is
And the own node address value set in the address setting circuit 8 are compared. Then, if the two values do not match, that is, if it is not the own node destination transmission frame, the process returns to step S5,
Be prepared to receive a transmission frame addressed to its own node.

In the case of the transmission frame addressed to the own node, the process proceeds to step S11 and the transmission right is acquired by receiving the token. Then, in the subsequent step S12, it is checked whether or not there is data to be transmitted from the host 3 or its own node, that is, whether or not there is a transmission request,
If there is a transmission request, a transmission frame for transmitting data is generated in step S13.

Specifically, the node address (destination address) peculiar to the destination node is set in DA202, the own node address (source address) set by the address setting circuit 8 is set in SA201, and then the transmission code 205 and transmission are set. Information 206
To generate a data transmission frame 250. Then, in step S14, this data transmission frame 2
50 is transmitted to the destination node according to a predetermined transmission control procedure. This transmission control procedure is publicly known and will not be described.

When the data transmission process is completed, the process proceeds to step S4, the token frame 200 is generated, and the token circuit 200 is generated.
Is transmitted to the transmission line 1 via the transmission line, the transmission right is transferred to the downstream node, and the process returns to step S5.

If the token frame is not received in step S8, the process proceeds to step S20, and the DA202 in the received frame is compared with the own node address value set in the address setting circuit 8 by the destination address determination circuit 13 as in step S10.
If the two values do not match, that is, if the transmission frame is not addressed to the own node, the process returns to step S5 to prepare for reception of the transmission frame addressed to the own node.

In the case of the transmission frame addressed to the own node, the process proceeds to step S21, the data transmission frame 250 addressed to the own device is received in the own node according to a predetermined transmission control procedure, and the step S22
It is checked whether the transmission information received in step 3 is the information to be sent to the host 3, and if it is the information to be sent to the host 3, the process proceeds to step S23, this information is disassembled and edited a little, and then connected to this node. To the host 3 and returns to step S5 to prepare for the next data transmission.

If it is not the data to be transmitted to the host 3, that is, if it is the communication data between the nodes, the process proceeds to step S30 to check whether the network configuration table has been sent from the master node by, for example, group broadcast communication. If the network configuration table is received, the received data is stored in the network configuration table 9 in step S26.

If the network configuration table is not received in step S25, the process proceeds to step S27, the process corresponding to the received data is executed, and then the process returns to step S5 to prepare for the reception of the next transmission frame.

As described above, in the present embodiment, only the master node can first generate a token and send (delegate) it to another node, and the other node receives the token from the master node and then receives the token. Without it, tokens cannot be generated. That is, the token is generated from only one node, and the tokens do not collide with each other on the transmission line 1.

Next, the network configuration construction processing in the above description will be described with reference to the flow chart in FIG.

In this embodiment, this network reconfiguration processing is performed only by the master node, and the other nodes receive the network configuration information from the master node, store it in the network configuration table 9, and transmit it according to the stored contents. To do.

This network reconfiguration process is performed when a token is lost at the time of system startup, that is, when a node that is part of the network is disconnected from the network due to power failure or failure. This is done when a node joins.

First, in step S40, the downstream node address, that is, the destination address is set to the set address of the self node, regardless of the downstream node address held in the network configuration table 9 until now, and in step S41, this downstream node address is set. Decrement by one and check in step S42 whether the destination address and the set value of the address setting circuit 8 are equal,
If they are not equal, the process proceeds to step S43, a transmission frame is generated using this address as the destination address, and is transmitted from the transmission line 1 via the transmission circuit 12. This transmission frame may be a control frame between nodes.

Then, in a succeeding step S44, it is checked whether or not the transmission of the transmission frame is successful. The means for identifying this varies depending on the transmission control procedure of each network, but is identified by, for example, returning an ACK response, which is an acknowledgment, at the node that has received the transmission frame.

If the transmission frame is not normally sent to the destination node (if the transmission fails), the other node operates (communication).
Assuming that the node is an impossible node, the process proceeds to step S45, and it is checked whether or not the destination node address value is the minimum address value defined in the network. If it is not the minimum address value, the process returns to step S41 and the destination node address value is set again by one. It decrements and tries transmission frame transmission using this new address value as the destination address.

In this way, the address value is gradually subtracted, and then the transmission frame is tried to be transmitted to the node having the address value.

If the subtracted address value reaches the minimum address value defined in the network, step S45
Then, the process proceeds to step S46, and the destination node address value is set as the minimum node address value specified in the network.
Return to S43. After that, the transmission of the transmission frame and the subtraction operation of the address value are repeated.

If the transmission of the transmission frame is successful, the step
The process proceeds from step S44 to step S47, and the node having the destination node address value at that time is stored in the network configuration table 9 as an operable node configuring the network.
Then, the process returns to step S41, and it is checked whether or not another operable node exists.

If the destination address and the own node address are equal in step S42, it means that the transmission processing of the transmission frame has been executed for all the nodes that make up the network, so the process proceeds from step S42 to step S50, In the process, it is checked whether or not there is a node that has successfully transmitted the transmission frame.

If there is no successful transmission node here, it indicates that all nodes other than the master node of the network system are in an inoperable state, so the process returns to step S40, and the network is transmitted until one of the nodes becomes transmittable. Execute the build process. As described above, in the present embodiment, the above-described processing is repeated until the transmission processing of the transmission frame to one of the nodes succeeds.

If there is a successful transmission node in step S50, step S
In step 51, the network configuration table stored in the network configuration table 9 is transmitted by group broadcast communication. The other nodes receive this broadcast communication, store it in the network configuration table 9 of their own node, and thereafter select a downstream node according to this network configuration table.

The above explanation is mainly about the recovery process when a node that falls out of the network occurs or when the network system starts up, but a node newly entering the network configuration asks its own node to circulate the token. There is a need. In order to achieve this, the node that should enter must monitor the transmission frame on the transmission path 1 and transmit as soon as it detects the token code 203 of the transmission frame (for example, when its own node address is between SA201 and DA202 of the transmission frame). Send data on the street, token frame 200
“Collision”, a token disappearance state is generated, and the processes from step S40 onward are executed.

Alternatively, this process may be performed at regular intervals.

Also, in the above description, a general transmission frame is transmitted,
Although the network configuration has been checked, the network configuration may be checked using a token frame instead of the transmission frame. In this case, first, only the master node may be designated as the network configuration table, the token is transmitted, and the transmitted token is returned to the own node.

[Second Embodiment] (Figs. 8 and 9) As described above, the master node in this embodiment plays an important role in recovery processing at the time of network start-up and token loss. It is a thing. Therefore, it is necessary to take sufficient measures against the failure of the master node. Therefore, in the present embodiment, a plurality of nodes that can be the master node are prepared, that is, a duplicated system or a multiplexed system of the master node is configured.

As described above, when the token is normally circulating, the master node performs the same operation as other nodes (hereinafter referred to as slave nodes). Further, the hardware configuration is such that the master node and the slave node simply add the timer circuit 10, and by providing the timer circuit 10 in all the nodes, any node can operate as the master node. . Therefore, for example, as a communication control processing procedure (firmware) in the CPU of each node in the network, both a control operation as a master node and a control operation as a slave node are provided, and the external (host)
It is desirable that either the control operation as the master node or the control operation as the slave node be selected and executed in accordance with an instruction from. The control operation selection instruction can be easily input by providing a control operation mode selection switch at the input / output port of the CPU 5, for example.

FIG. 8 shows a configuration example of the node in this case. This is the first
A timer circuit 10 and an operation mode selection circuit 14 are added to the circuit configuration shown in the figure. This operation mode selection circuit 14
Can be composed of, for example, a switching switch. FIG. 9 shows an external view of a node when a switching switch is used as the operation mode selection circuit 14.

As shown in FIG. 9, the switching switch 14a can be operated from the outside, and when the operating master node stops operating due to a failure or the like, another operating mode is switched to the master node as another slave mode. You can

[Third Embodiment] (FIG. 10) In the second embodiment, the master node function and the slave node function are selected by switching by the operation mode selection circuit 14, but this selection is switched according to the instruction input from the host 3. May be.

Generally, the host 3 is provided with a man-machine interface such as a personal computer shown in FIG.
Many are provided with 31 and a key input unit 32, and it is possible to instruct the switching of the master node / slave node function by a key operation of the key input unit 32 or the like.

As a result, it is possible to switch the processing function of the node 2 without the need for an operation on the node 2, which normally has little human intervention.

At this time, the node 2 sends, for example, the timeout information of the timer circuit 10 to the host 3 via the interface circuit 7, and when the host 3 receives this timeout information,
It may be controlled to display, for example, "token disappearance" information 31a on the display surface of the display device 31 of the host 3. When the operator confirms the display 31a indicating "token disappearance", he / she inputs the node function switching instruction input key 32a arranged in the key input section 32, and operates the node connected to the own device as the master node. Make a designated input to
According to this key input, the interface circuit 7 of the node 2
Specify to operate as a master node to CPU5 via. Upon receiving this designation input, this node executes the control operation as the master node shown in FIG. 6, reconstructs the network, and sends the token to the downstream node. At this time, if the function of the connected node of the own device is displayed on the display surface of the display device 31 (31b), the operator can always confirm the connected node function.

[Fourth Embodiment] (FIG. 11) Further, in the host 3 connected to the network, which controls particularly important processing in the network, for example, in a file device, a central processing unit, a mass storage device, etc. , 11th
As shown in the figure, multiple (eg, two) for the network.
In many cases, the connection is made through the node to improve reliability and strengthen communication capability. In the case of such a configuration, it is desirable that one of the nodes connected to this central processing unit be made to function as a master node so that the state of the node can be managed by the host side. It is one of these nodes.

In this case, there is also a method of operating one of the nodes as a master node and the other as a slave node in the normal case, and switching the other slave node to the master node when one master node goes down. This eliminates the need to find out which host of the network the master node is connected to, even if the node that was functioning as the master node goes down, the master node that changes to it will function as the master node before that. It is possible to immediately recognize that it is in the vicinity of the node in which it was operating, and it is possible to take quick and accurate troubleshooting.

Since any of the methods described above can potentially hold a plurality of master nodes in the network, it is possible to build a robust network system against failures in the master node.

In the above description, the token bus type network is used as a reference, but the present invention is not limited to this, and the present embodiment can be applied to a token ring type network configuration.

As described above, according to the present embodiment, token transfer can be performed reliably in any case, and even if token transfer cannot be performed normally, the network transmission can be performed without substantially impairing the data transmission efficiency. Can be rebuilt.

As described above, in this embodiment, by providing the master node only in the network, there is no conflict and collision state at the time of generation and transmission of tokens in the past, and the token circulation start processing is executed synchronously. It has the advantage of saying that.

In addition, it eliminates the need for conventional collision detectors,
It can be cheap in terms of cost.

Furthermore, since the asynchronous processing is eliminated, the processing procedure can be made extremely simple, and the processing overhead such as the communication control procedure can be minimized.

Further, even if the master node goes down due to a failure or the like, another slave node can be easily made the master node, and a network resistant to the failure can be constructed.

[Effects of the Invention] As described above, according to the present invention, when the system is started up and a new transmission device enters the network,
When a transmission device to which the token should be transferred is searched and a transmission device to which the token should be transferred is found, a normal transmission device in the network system is notified by notifying a plurality of transmission devices of the network configuration table as the search processing result. Can promptly start data transmission.

[Brief description of drawings]

FIG. 1 is a block diagram of nodes constituting a network system according to an embodiment of the present invention, FIG. 2 is a network configuration diagram, and FIG. 3 is a token of a network token passing system shown in FIG. Cyclic transition diagram, Fig. 4 is a token transition diagram of the token passing system in the case where there is a partially inoperable node of the network shown in Fig. 2, and Figs. 5 (A) and 5 (B) show the present embodiment. FIG. 6 is a configuration diagram of a transmission frame used in FIG. 6, FIG. 6 is a general data transmission control flow chart in the node of this embodiment, FIG. 7 is a network construction processing flow chart in this embodiment, and FIG. A block diagram of nodes constituting the network system of the embodiment, FIG. 9 is an external view of a node of another embodiment of the present invention, and FIG. 10 is an external view of a node and a host of another embodiment of the present invention. , FIG. 11 is a configuration diagram of the net work of another embodiment of the present invention. In the figure, 1 ... Transmission path, 2,100 to 170 ... Node, 3 ... Host, 4 ... Token discrimination circuit, 5 ... CPU, 6 ... Memory circuit, 7 ... Interface circuit, 8 ... Address Setting circuit, 9 ... Network configuration table, 10 ... Timer circuit, 11 ... Reception circuit, 12 ... Transmission circuit, 13 ... Destination address discrimination circuit, 14 ... Operation mode selection circuit, 31 ...
... display device, 31a ... node function display, 32 ... key input part, 32a ... node function switching instruction input key, 203 ... token code, 205 ... transmission code.

Claims (1)

[Claims] 1. A network control method of a network system in which a plurality of transmission devices are connected to each other via a communication medium to obtain a transmission right by a transmission device which has acquired a communication right by a token which is a communication right transfer instruction. A specific transmission device among the devices makes it possible to newly generate a token when a token is lost due to an abnormality occurring in the network system due to the entry of a new transmission device into the network and when the system is started up. Is a destination address setting unit that sets an address value of its own device as an initial value and shifts the address value one by one from the initial value, and sets the destination address, and the address value set by the destination address setting unit is a unique address value. A transmission frame for checking whether the transmission device can operate or not. Transmission means for signal for, when the response signal from the transmission apparatus that has transmitted the transmission after the transmission frame of the transmission frame by the transmission means sent back,
Storage means for storing in the network configuration table the address value of the transmission device that transmitted the transmission frame; setting the address value by the destination address setting means, transmitting the transmission frame by the transmission means, and storing the address value by the storage means. The control unit has a control unit that repeatedly executes storage for all transmission devices, and a notification unit that notifies the address values stored in the network configuration table to a plurality of transmission devices that configure the network. Even if the transmission command is sent to all the transmission devices, if there is no transmission device returning the response signal, the address value is set from the beginning again by the destination address setting means and the transmission frame of the transmission means is set from the beginning. Repeat transmission and storage of address values by the storage means for all transmission devices When there is a transmission device that executes and returns a response signal to the transmission command, token transmission processing is performed to enable data transmission, and each of the plurality of transmission devices that configure the network transfers the token. In the network control method, the token is sent to another transmission device based on the contents of the network configuration table notified from the specific transmission device.